1. Field of Invention
The present invention relates to attachment structure for mounting refractory ceramic fiber insulation units in insulating and sealing rings for ladle preheaters.
2. Description of Prior Art
U.S. Pat. Nos. 4,229,211 and 4,364,729 related to ladle preheating systems which incorporate a refractory fiber lined wall or lid which mechanically seals against the rim of the ladle. A burner and flue arrangement are centrally located on the wall or lid. The mechanical sealing function is critical to the efficient containment of the combusted gases. In these systems, substantially the entire rectangular support frame or plate was covered with refractory ceramic fiber modules, such as those according to U.S. Pat. No. 4,001,996. These modules, typically having square prismic shape, were installed in a uniform grid pattern. Since the ladle rim was usually of circular or oval construction, the modules in the outer corners of the frame served no useful function other than support for the modules which did lie within the seal area. Establishing a circular or oval seal area with a uniform square grid pattern involved the use of inactive modules. This increased the cost of construction and maintenance. The ladle rim was a generally uneven surface and the modules during repeated sealing actions were worn and displaced. Joints between adjacent modules in the sealing area were often forced apart because of this effect. This caused loss of sealing effectiveness and the possibility of damaging heat leakage.
U.S. Pat. No. 4,223,873 disclosed a ladle preheater with a circular seal of ceramic fiber compaction material. However, no structural details of this seal, or how it was to be installed and supported, were given. The rectangular ceramic fiber modules used for furnace wall insulation, such as those of U.S. Pat. No. 4,001,996 mentioned above, and others on the market, did not lend themselves to forming circular seals. There are several ways that attempts could be made to use them, but none was satisfactory. These square or rectangular modules could be cut to fit a circular or oval seal pattern. This would cause material waste and increased installation costs. Even more importantly, however, the structural integrity and thus the compressive effects between adjacent modules would be reduced. Alternatively, these modules could be arranged about a generally circular pattern, leaving gaps in spaces between adjacent modules where curved surfaces were necessary. This would require stuffing to be inserted in the spaces, increasing installation costs and resulting in irregular compressive effects.